MELT butter in large saucepan. Add mushrooms; cook and stir 5 to 6 min. or until tender. Stir in flour; cook on low heat 15 min., stirring frequently. Meanwhile, heat broth in medium saucepan on medium heat. Add chicken; cook 6 to 7 min. or until done (165ºF). Remove chicken from broth; set aside.
ADD broth gradually to mushrooms, stirring constantly; cook on medium heat 5 min. or until broth is thickened, stirring frequently. Chop chicken. Add to soup. Stir in cooking creme and rosemary; cook 2 to 3 min. or until heated through, stirring frequently. Season with salt and pepper.
SERVE topped with bacon, if desired.